The answers you suggested to your own question about the use of contrast in Robert Frost’s poem “There Are Roughly Zones” are very good ones. Here are some additional possibilities to consider.

The poem opens with a contrast between humans safe and warm inside while nature is bitterly cold outside (1). Already, then, a contrast between nature and mankind is being implied. Later this contrast will become a major theme of the poem.

In line 3, nature at first appears so powerful that it even seems a threat to the house. In other words, the safe distinction between inside and outside and between man and nature asserted in the opening line now seems threatened. By the end of the third line, however, man’s ingenuity seems to protect him from the threats of nature.

Ironically, the next contrast is between one aspect of nature (the tree) and other aspects of nature (the cold and the wind combined). But the peach tree would probably never have grown this far north on its own if man had not intervened and planted it there. The tree, then, is almost a symbol of man’s tendency to interfere with nature and to try to manipulate nature (the tree) to his own purposes.

Ironically, then, just as nature had seemed about to interfere with humans in line 3, so humans have definitely interfered with nature in line 6. Humans have attempted to ignore natural laws and have tried to impose human will on nature.

Another contrast implied in the poem is the contrast between the “far north” (6) and the more temperate zones further south.

The growth of the peach tree so far north may actually lead to the tree’s demise, so that the poem plays with yet another contrast – the contrast between life and death. At one time the tree had leaves; soon it may be barren of leaves (one more contrast).

Another contrast – between soul and mind – is suggested in line 7, while lines 8-10 imply a contrast between man’s aspirations and the necessary and inevitable limits on those ambitions:

What comes over a man, is it soul or mind---

That to no limits and bounds he can stay confined?

You would say his ambition was to extend the reach

Clear to the Artic of every living kind.

Line ten implies a contrast between the Arctic (as a region in which most things, especially most vegetation, cannot live) and the temperate zones (in which many different kinds of life abound).

Line 11 implies a contrast between natures that are easy to teach (such as the natures of dogs, for instance) and natures that are hard to teach (such as man’s).

Line 12 comments on two concepts – right and wrong – normally contrasted, but it suggests that absolutely firm contrasts between these two distinctions can never be firmly drawn.

Contrasts continue to be either stated or implied in lines 16 and 17 (“should rise” / “went down”), in line 19 (winter vs. spring), in line 20 (growth vs. non-growth).

Finally, in line 21, the poem returns to the key contrast between man’s ambitions and the limits imposed on those ambitions, particularly by nature.